Draftsman&#39;s instrument



March 14, 1967 B. w. HAZELTON 3,308,542

DRAFTSMAN'S INSTRUMENT Filed Dec. 21, 1964 2 Sheets-Sheet 1 March 14, 1967 5. w. HAZELTON DRAFTSMAN'S INSTRUMENT Filed Dec.

2 Sheets-Sheet 2 HHI MOE

United States Patent M 3,308,542 DRAFTSMANS INSTRUMENT Burton W. Hazeiton, Kirk-wood, Mo. I-Iazeiton Products, Inc, Box 266, Valley Park, Mo. 63088) Filed Dec. 21, 1964, Ser. No. 419,640 9 Claims. (Cl. 3379) The invention relates to a drafting apparatus which avoids the use of a T square slidable manually along the straight marginal portion of a drawing board or the use of a drafting machine which comprises at least two arms with respective ends pivoted to each other and movable toward and away from each other over a drawing board.

Among the objects of the invention are to facilitate drafting operations by mounting a single drafting blade element corresponding to the blade of a T square to move over a drawing board so that the blade is readily shiftable to various positions parallel to each other over the board and is readily adjustable to any desired angle to a given base line on the board. It is desired also be render the entire apparatus readily portable for convenient use in the ofiice, or in the field or in an automobile or on the lap of a user and otherwise where the familiar drafting machine clamped to the margin of a drawing board would be inconvenient or inoperable.

The invention comprises generally the pivoting of a support arm near the center of the board and beneath the board, mounting a straight edge or drafting blade on the swinging end of the support arm and extending therefrom over the board.

In the accompanying drawings illustrating selected embodiments of the invention:

FIG. 1 is a top view of the apparatus drawing board and associated structure, the board being broken away in part to better show the mechanism.

FIG. 2 is a side view of the board, mechanism, mounting base and a pedestal.

FIG. 3 is a vertical section on line 3-3 of FIGS. 1 and 4, drawn to an enlarged scale.

FIG. 4 is a horizontal section on line 4-4 of FIG. 3.

FIG. 5 is a detail vertical section corresponding generally to FIG. 3 but taken at a different angle diametrically of the blade mounting head on line 55 of FIG. 4 and showing a released clamping of some parts.

FIG. 6 is a similar detail section drawn to a larger scale and showing the same parts clamped together.

FIG. 7 is a detail section on line 77 of FIG. 3.

FIG. 8 is a detail top view of the central pivot mounting structure shown in FIG. 1 and on a larger scale.

FIG. 9 diagrammatically illustrates another form of the invention.

The apparatus shown in FIGS. 1-6 includes a drawing board or fiat base 1 which may be secured to a pedestal 3 or may be placed upon a table, a cabinet, a trestle, the

lap of the user or other support. Fixed to the base is a hollow upright shaft 5 (FIGS. 3, 4) with a flange 6 at its upper end having a depending rim forming a drum 7. The flange supports a drawing board 8 having a circular periphery 9 as shown in FIG. 1. Fixed on shaft 5 is the inner race 11 of a double ball bearing 12, the outer race 13 of which mounts a spider 15 having diametrically disposed sockets 16, 17 opening radially of the shaft and drawing board.

A horizontal tubular rigid support arm 19 is seated at one end in socket 16 and extends therefrom radially of the shaft between base 1 and board 8 and at its outer end is received in and carries the sleeve 20 (FIG. 3) of a shallow cup 21 slidably keyed to arm 19 and mounting the outer race 23 of a self-aligning double ball bearing 24, the inner race 25 of which mounts the hub of a pulley 27. A steel band belt 29 passes around drum 7 and pulley 3,3@8,542 Patented Mar. 14, I967 27. When arm 19 is swung around shaft 5, belt 29 r0- tates pulley 27 to the same degree as the arm but in the opposite direction.

The tension on belt 23 is controlled by the adjustment of a screw 30 threaded into a plug 31 inthe outer end of arm 19. The screw head thrusts against a bearing washer seated on thebottom of sleeve 20. The screw head forms a worm gear 30a. An upright worm 32 (FIG. 7) is journaled in sleeve 20 and meshes with gear 30a and has a screwdriver slot in its lower end whereby it may be turned to rotate screw 30 and slide cup 21 to tighten or loosen belt 29. The key for holding sleeve 20 and cup 21 against turning on arm 19 is an arcuate segment 31a slidably fitting in a longitudinal slot 31s in plug 31 and anchored to arm 20 by a screw x.

A disk 33 includes an upstanding boss 34 shouldered at 34a and 34b (FIG. 3). A blade head 35 is rotatably seated on shoulder 34a and has a radial bracket 35a. An elongated blade 36 forms a drafting straight edge and is dovetailed into bracket 35a and is detachably secured thereto by screws 37. A recess in disk 33 contains a 360 protractor 66 (FIG. 1) and a corresponding Vernier 65 is located on the flange of head 35. The head may be rotated and locked either at fixed increments or at any predetermined setting relative to the protractor scale of disk 33. Disk 33 is rotatably seated on pulley 27 and has a depending circular rib 33a surrounding an upstanding circular platform 27a on pulley 27, but normally is clamped to the pulley by a screw 41. The clamping of disk 33 to pulley 27 is relieved by manual rotation of screw 41 by its head 41a then swinging the blade head and disk assembly about the upstanding circular platform 27a to the desired position and then tightening clamping screw 41. This adjustment may be used advantageously to align the straight edge 36 with a base line on drawing D with the protractor set at zero. The ball bearing 24 may be radial or it may have an arcuate outer race 23 to accommodate inclination of head 35 and blade 36 so that the latter may contact board 8. I

A handhold knob 40 is secured to head 35 by screws 40a (FIG. 3) and is grasped by the user .to swing head 35 and the outer end of arm 13 about central shaft 5. The action of drum 7 and pulley 27, through belt 29, normally maintains the blade in successive parallel positions as head 35 is swung manually about shaft 5. This is due to the locking of clamping screw 41 as described, and secondly, by locking the head 35 at the desired angle selected on the protractor 66 and vernier 65. The following elements comprise the locking devices: A nut 38 on the threaded-upper end of boss 34 tightens a washer 39 against shoulder 34b. The washer projects over a recess 45 in head 35 (FIG. 6). The recess receives a friction plug 46. A pin 47 is splined into plug 46 and is anchored therein by a slotted nut 48 which may be turned by a screwdriver, inserted through an aperture A in disk 33, to adjust the pin in the head. A clutch actuating lever 49 is threaded onto the upper end of pin 47 and when turned clockwise (FIG. 4) will draw plug 46 up to the opposing faces of washer 39 and head 35, thus clamping head 35 to disk 33 and assuring that head 35 and blade 36 turn With disk 33 as the latter is rotated by belt 29. This will maintain blade 36 in successive parallel positions. But if clamp 46-49 is released (FIG. 5) by shifting finger piece 49 counterclockwise, and freeing the clutch, head 35 and blade 36 may be readily rotated about their common axis on disk 33 and independently of the swinging of arm 19 on shaft 5. Such rotation may be subject to a ratchet control provided by a ring 50 secured in an upwardly facing recess in disk 33 and having a series of notches 51 (FIG. 4) on its inner periphery and preferably spaced 15 apart. Head 35 has a recess in its underfac'e receiving a pawl 54 (FIG. 4) in the general plane of ring 50 and is pivoted on a pin 55 .in the head and includes a tooth 54a thr-ust toward the notches in ring 56 by spring 56. A plate 58 lies in a recess in the upper face of disk 33 and is secured to an upright pin 59 journaled in head 35. One end of the plate underlies pawl 54. An upright roller 61 is loosely positioned in a slot in the swinging end of plate 58. A compression spring 6% is connected at 63 to the inner end of plate 58- and at its other end to an anchor 64 depending from head 35 and normally urges plate 58 clockwise (solid lines FIG; 4) to thrust roller 61 against pawl 54 to hold the pawl tooth in a selected notch 50, thus positively lockingv disk 33 and head 35 against relative angular movement. A finger piece 62 issecured to and extends laterally from pin 59.

It finger piece 62 and pin 59 shift plate 53 anticlock wise, roller 61 moves out from behind pawl 54 and as connection 63 moves past pin spring 60, there is an over center action further shifting the plate and roller away from pawl 54. This will cut out the ratchet act-ion so that head 35 and straight edge 36 may be turned free of disk 33 to position head 35 at any desired angle relative to disk 33, irrespective of the 15 increments afforded by notches 51, and then clamp 49 may be tightened to hold head 35 and disk 33 in the adjusted position. This may be used to select a desired angle other than 15 as may be measured by use of the vernier scale 65, 65 (FIG. 1) on head 35 and ring 50 respectively.

The upper face of flange 6 on drum 7 is recessed at 6:1

to receive a pawl 70 (FIGS. 3, 8), corresponding to pawl 54 previously described, which is pivoted on the flange at 71 and has a tooth 72. The pawl is thrust away from shaft 5 by a spring '73. A ring 75 is secured to the undernotch-engaging position so that board 8 and shaft 5 are held in a selected angular relation. An arm 79 on cam 76 is connected by a cable 80 to a bell crank 81 (FIG. 1) pivoted at'82 to table 1 and readily operable manually to release pawl 70 from locking cam 76 so that the-pawl may ride over the notches in ring and permit ready rotation of the board to a selected angular position on table 1. Upon release of bell crank 81, cam 76 will positively hold tooth 72 in the new table-board locking position. 1

Seated in socket 17 on drum 15 is a relatively'sho'rt arm 85 radiating in the opposite direction to arm 19. The-outer end of arm 85 adjustably mounts a weight 86 (FIG. 1) which counter'halances the parts mounted on the outer end of arm 19 and avoids undue dragging of the left hand portion of'blade 36 along the drawing surface (due to the weight of members 21, 27, 35, 4%). Also,

when the lower por'tionof base 1 is tilted downwardly from the horizontal, to facilitate the users access to the upper margin U of the drawing, weight 36 will offset the tendency of these members to swing downwardly about shaft 5. A pad 87 of felt or the like offers some frictional resistance to the swinging of arms 19,-85 and the parts mounted thereon. Preferably base 1 includes trays 88 below the level of arms 19, 85 for pencils and other supplies.

FIG. 9 illustrates a form of the invention in which the apparatus includes a table-like base member 90 mounting an upright shaft 92 to the upper end of which is attached a rectangular drawing board 93-and the left hand end of a support arm 91 pivoted on shaft 92 projects substantially farther beyond the left hand edge of the board in order to swing around the left hand corners of the board. The outer end of the support arm carries a straight edge drafting blade 97 which is adjustable on the swinging end of arm 95 and includes a pulleyconnected to a drum on shaft 92 as are similar parts in FIGS. 1-6, The straight edge is shifted to different positions across the board, but normalty is maintained at a constant angle to a base line on the board or on a drawing sheet applied to the board, as in the structure previously described.

The structures disclose-d may be used as described in a diernakers layout table for marking steel blocks, or in other drafting-like operations, and the terms draftsmans apparatus, drawing board and drawing blade are intended to apply to similar items modified for size, strength, adjustability, etc., which are adapted for such similar usages.

The details of the structure may be varied substantially without departing from the spirit of the invention and the exclusive use of those modifications coming within the scope of the claims is contemplated.

What is claimed is: 1. Draftsmans apparatus comprising a drawing board, an elongated carrier arm beneath said board and having a vertical axis pivot mounting thereon at a point spaced inwardly from an edge of the board,

said carrier arm extending substantially parallel to the plane of the board and beyond said edge,

an elongated drafting blade overlying the board and extending beyond-said edge and having a vertical axis pivot mounting on said carrier arm,

and mechanism connecting the two pivot mountings and maintaining a predetermined angular relation between the drafting blade and a selected straight line on the board as the carrier arm is moved about its pivot mounting on the board,

the pivot mounting for the elongated carrier arm on the board and the pivot mounting for the elongated drafting blade on the elongated carrier arm each comprising a self-aligning ball bearing including inner and outer races inclinable relative to each other transversely of the pivot axis and accommodating v ,the mechanism maintaining the predetermined angular relation comprises a drum fixed to the pivoted end of the carrier arm and rotating with the arm about its pivot on the board,

a pulley fixed to the pivoted end of the blade and rotatable relative to the adjacent end of the carrier arm, said drum and pulley having equal circumferences,

and a driving belt passing over said drum and pulley and providing for their simultaneous rotation in the same direction and to the same degree about their respective axes as the carrier arm is rotated on its pivot.

3. Draftsmans apparatus comprising a drawing board,

an upright axis pivot member beneath said board and spaced substantially centrally inwardly from the edges of the latter,

a singleelongated rigid carrier arm beneath the board and pivoted at one end to and extending from said pivot member substantially parallel to the board and beyond the edge thereof and'movable' about said pivot member,

an elongated drafting blade overlying the board and having a portion extending beyond the edge of the board and provided with a mounting pivoted directly on said carrier arm and movable about said mounting over substantially the entire board,

and mechanism connecting said pivot member and said mounting and holding said drawing blade to successive parallel positions as said carrier arm is swung about said pivot member.

4. Draftsmans apparatus comprising a drawing board having an arcuate peripheral portion,

an elongated radial carrier arm beneath the board having a vertcial axis pivot mounting on theboard substantially at the center of said arcuate peripheral portion, said carrier arm being movable about said mounting in a plane parallel to the board, said carrier arm projecting beyond said arcuate peripheral portion,

an elongated drawing blade overlying the board and having a single pivot support on the outer end of said carrier arm to move about the same in a plane substantially parallel to the board,

and mechanism connecting said pivot mounting and said blade and maintaining a predetermined angular relation between said blade and a given straight line on said board as said carrier is moved about said pivot mounting.

5. Draftsmans apparatus comprising a stationary horizontal mounting member,

a drawing board spaced above said mounting member,

an upright shaft fixed on said mounting member and drawing board and positioned inwardly from the peripheries thereof,

an elongated carrier arm pivoted on said shaft and extending therefrom between the mounting member and drawing board and projecting beyond the periphery of the board and movable freely about said shaft to different angular positions,

a drafting blade pivoted to the projecting end of said arm and extending thereform over the top of the drafting board,

and mechanism connecting the pivoted portion of the support arm and the pivoted end of said blade and maintaining equal angular rotation of the arm and blade on their respective pivots, but in opposite directions, as the arm is swung about said shaft.

6. Draftmans apparatus according to claim 5 which includes a manually releasable clamp for readily resetting the angular relation between the arm and the blade.

7. Draftsmans apparatus according to claim 5 which includes means for manually selectively vary the angular relation between the arm and the blade without affecting the action of the mechanism.

8. A draftmans apparatus comprising a drawing board having a circular periphery,

a support arm beneath the board and parallel to the plane of the board and having a pivot at the center of the board,

said arm projecting radially beyond the periphery of the board and being movable freely about its pivot throughout an arc of 360,

a drawing blade pivoted at one end to the outer end of said arm and extending from its pivot across the top of the board,

and mechanism maintaining a desired angular relation between the blade and a given diameter of the board throughout movement of said support arm about its pivot on the board.

9. Portable drafting apparatus comprising a table-like member,

an upstanding shaft fixed to the central portion of said member,

a drum freely rotatable on said shaft,

a circular drawing board fixed on said shaft above said drum, said shaft, drum and board being concentric,

a support arm fixed on said drum and radiating therefrom between the table and drawing board with an end projecting beyond the edge of the drawing board,

a pulley on the projecting end of said arm and rotatable about an upright spindle thereon and having the same circumference as said drum,

a drawing blade secured at one end to said pulley and extending therefrom over said drawing board,

and a belt between said drum and pulley and rotating them in unison, as said support arm is swung about said shaft and maintaining the drawing blade at a constant angle to a diameter of said board.

References Cited by the Examiner UNITED STATES PATENTS 389,472 9/1888 Hopkins 3378 2,459,216 1/1949 Booth 33-78 2,536,142 1/1951 Sanders et a1 3379.3

FOREIGN PATENTS 235,790 4/ 1945 Switzerland.

250,926 7/ 1948 Switzerland.

266,128 4/1950 Switzerland.

LEONARD FORMAN, Primary Examiner. H. N. HAROIAN, Assistant Examiner. 

1. DRAFTSMAN''S APPASRATUS COMPRISING A DRAWING BOARD, AN ELONGATED CARRIER ARM BENEATH SAID BOARD AND HAVING A VERTICAL AXIS PIVOT MOUNTING THEREON AT A POINT SPACED INWARDLY FROM AN EDGE OF THE BOARD, SAID CARRIER ARM EXTENDING SUBSTANTIALLY PARALLEL TO THE PLANE OF THE BOARD AND BEYOND SAID EDGE, AN ELONGATED DRAFTING BLADE OVERLYING THE BOARD AND EXTENDING BEYOND SAID EDGE AND HAVING A VERTICAL AXIS PIVOT MOUNTING ON SAID CARRIER ARM, AND MECHANISM CONNECTING THE TWO PIVOT MOUNTINGS AND MAINTAINING A PREDETERMINED ANGULAR RELATION BETWEEN THE DRAFTING BLADE AND A SELECTED STRAIGHT LINE ON THE BOARD AS THE CARRIER ARM IS MOVED ABOUT ITS PIVOT MOUNTING ON THE BOARD, THE PIVOT MOUNTING FOR THE ELONGATED CARRIER ARM ON THE BOARD AND THE PIVOT MOUNTING FOR THE ELONGATED DRAFTING BLADE ON THE ELONGATED CARRIER ARM EACH COMPRISING A SELF-ALIGNING BALL BEARING INCLUDING INNER AND OUTER RACES INCLINABLE RELATIVE TO EACH OTHER TRANSVERSELY OF THE PIVOT AXIS AND ACCOMMODATING TILTING OF THE ELONGATED CARRIER ARM TO AND FROM THE BOARD AND TILTING OF THE DRAWING BLADE TRANSVERSELY OF ITS LENGTH TO CONTACT ONE FACE OF THE BLADE WITH THE DRAWING BOARD. 